Thermoelectric cooler aids remote, hazardous spectroscopy

Truly new technologies are rare. So innovation usually means adapting familiar methods and equipment to improve quality and cut costs.Thermoelectric cooling, for example, has long used dissimilar semiconductor materials and dc current to create temperature differentials without compressors, fluorocarbons, and piping.

By Staff April 1, 1999

Truly new technologies are rare. So innovation usually means adapting familiar methods and equipment to improve quality and cut costs.

Thermoelectric cooling, for example, has long used dissimilar semiconductor materials and dc current to create temperature differentials without compressors, fluorocarbons, and piping. It’s been refined over the decades and is now used in many applications, such as cooling electronic enclosures in hazardous locations, including NEC Class 1, Division 2. These environments are typical in oil and chemical refineries, foundries, and other places adjacent to gases or vapors.

To improve efficiency and reduce maintenance costs, Guided Wave Process Analytical Systems (El Dorado Hills, Calif.) recently installed an AHP-1200XP solid-state cooling system from ThermoElectric Cooling America Corp. (TECA, Chicago, Ill.) to cool its near-infrared (NIR) radiation remote spectroscopy system. A division of UOP LLC, Guided Wave’s spectroscopy equipment collects real-time data from liquids, gases, slurries, and polymer-based films during on-line production processes. Its spectrophotometer transmits radiation through fiber-optic cables to a probe installed in a reactor or process line. Data are interpreted by the system’s software to determine composition or physical characteristics of materials being processed.

Protection, maintenance

Though it sometimes can be installed further away from the probe, the spectrophotometer often must be installed in hazardous environments. Its electronics are protected in a sealed enclosure, which is purged with dry nitrogen to create positive pressure and a safe environment for the spectrophotometer’s internal equipment. However, this sealed enclosure also traps heat from the electronics, which are now cooled with TECA’s ThermoElectric system.

Because AHP-1200XP doesn’t use air or water filters, Guided Wave’s personnel are spared previously required maintenance. ‘Because the UOP system can be located in hazardous and frequently inaccessible locations in the facility, there had been a tendency to ignore the need for filter replacement. This affected efficiency and often the operation of conventional cooling systems,’ says Cal Reynolds, Guided Wave’s project engineering group supervisor. ‘The thermoelectric cooling system’s lack of moving parts also enabled us to minimize other maintenance concerns.’

One AHP-1200XP unit operates at a standard capacity of up to 1,000 Btu/hr. However, added units can be installed to accommodate applications with higher heat loads.

In thermoelectric cooling, semiconductor materials with dissimilar characteristics are
connected electrically in series and thermally in parallel so two junctions are created.

For more information, visit www.controleng.com/freeinfo .